Identifying Optimal Fan Compressor Pressure Ratios for the Mixed-Stream Turbofan Engine

Abstract

This paper describes a heuristic approach for determining the optimal fan compressor pressure ratio for a e xed set of mixed-stream turbofan engine parameters. During the aircraft design process, it is important to select an enginedesign thatminimizes fuel consumption while producing the thrust required by the variousaircraftmission e ight conditions. Although the most fuel-efe cient values of such parameters as bypass ratio and high-pressure compressor (core) pressure ratio depend on the integrated effects of the various e ight altitudes, Mach numbers, and thrusts required throughout the mission, it is possible to heuristically locate the most efe cient fan compressor pressure ratio to complement other engine parameters independent of the mission. At this optimal value, thrustspecie c fuel consumption is approximately minimized and specie c thrust is approximately maximized at all e ight conditions. Exploiting the observed engine performance characteristics, optimal fan compressor pressure ratios were successfully located for a wide range of bypass ratios and core compressor pressure ratios across a variety of on- and off-design e ight conditions.